There is known a sensor apparatus which effects measurement on properties or constituents of an analyte liquid with use of a detection element such as a surface acoustic wave element (refer to Patent Literatures 1 to 3, for example).
For example, in a sensor apparatus using a surface acoustic wave element is provided with, on a piezoelectric substrate, a detection section which reacts with a constituent contained in an analyte liquid, and is configured to detect the properties or constituents of the analyte liquid by measuring variation in surface acoustic waves propagating through the detection section. Such a measurement method using the surface acoustic wave element or the like has the advantage over other measurement methods (for example, enzymatic method) in that it allows easy simultaneous detection for a plurality of characteristics to be inspected.
However, each conventional sensor apparatus using a detection element such as the surface acoustic wave element has no mechanism capable of liquid suction built therein. Thus, in order to enable an analyte liquid to flow into the detection section, the following procedural steps are required: suction of the analyte liquid using an instrument such as a micro pipette; and delivery of the sucked analyte liquid into the detection section. This leads to an increase in the complexity of measurement operation. Furthermore, the necessity of preparation of extra instruments leads to scale-up of the measurement apparatus as a whole.
There is also known a sensor apparatus which adopts a detection method which differs from the detection method using a detection element such as the surface acoustic wave element. In this construction, a reagent containing, for example, an enzyme is applied in advance to a measuring electrode, and, a target contained in an analyte liquid is caused to react with the reagent-bearing part for the reading of electric current variation in the measuring electrode (refer to Patent Literature 4).
In Patent Literature 4, there is disclosed a technology that enables the sensor apparatus to effect suction of an analyte liquid on its own by using capillarity. According to this technology, an elongate pathway for the supply of an analyte liquid is led out to the reagent-bearing part of the measuring electrode to suck an analyte liquid so that it can be directed to the reagent-bearing part under capillarity.
Inconveniently, the analyte liquid measurement method as disclosed in Patent Literature 4 that involves application of a reagent containing an enzyme or the like to the measuring electrode does not lend itself to inspection for a plurality of characteristics because of limitations upon the number of measurable characteristics to be inspected.
In the sensor apparatus disclosed in Patent Literature 4, its measuring section is implemented by applying a reagent to an electrode, wherefore the thickness of the measuring section is equivalent to the thickness of the electrode, that is; the measuring section is very thin. This makes it possible to place the elongate pathway for the supply of analyte liquid so as to reach the measuring section without discontinuity.
On the other hand, in the sensor apparatus using a detection element such as the surface acoustic wave element, the detection element is formed of a piezoelectric substrate or the like, and thus has a certain thickness. In this case, even if the technology disclosed in Patent Literature 4 is applied, the pathway for analyte liquid supply may be obstructed by the detection element, thus making it difficult to cause an analyte liquid to flow into the detection section.